There are clear indications that catch size and quality have declined, often dramatically, and in many areas larger and longer-lived species have disappeared entirely from commercial catches.
Large open water fish like tuna have been a shared fisheries resource for thousands of years but the stocks are now dangerously low. In 1999 Greenpeace published a report revealing that the amount of bluefin tuna in the Mediterranean had decreased by over 80 percent in the previous 20 years and government scientists warn that without immediate action the stock will collapse.
Key to the recovery and long-term sustainability of any stock is the protection of its young, juvenile fish so that these can reach maturity and spawn. As overfishing has depleted the larger adult fish, it is increasingly the case that juveniles and smaller fish are caught and kept - often despite restrictions prohibiting this. Indeed, spawning and nursery grounds are deliberately targeted in some fisheries.
Other fisheries, such as for swordfish, are unregulated affording no protection to the juveniles. But even where restrictions do exist, these are openly flouted, as a recent Greenpeace investigation of fish markets in Greece exposed.
By-catch is the accidental capture of non-target species from seabirds to juvenile fish, which is immediately discarded back into the sea dead or dying. The discard rates for Mediterranean fisheries are between 20 and 70 percent of catches according to water depth and season.
Turtle caught on a Spanish longline.
Illegal, Unregulated and Unreported fishing
The lack of effective management systems and increased commercial pressure on our dwindling fishery resources has helped fuel an illegal, unregulated and unreported (IUU) fishing industry. A good example is the extensive use of illegal driftnets in the Mediterranean Sea.
Of all the Mediterranean countries, Spain is the only one to have adopted a National Plan of Action to combat the problem of IUU fishing, as mandated in the International Plan of Action of the United Nations Food and Agriculture Organization.
No regional register for fishing vessels exists and there is a lack of funding and infrastructure to implement the laws intended to combat illegal fishing in international waters.
The impact of driftnets, often up to 17km in length, has long been scrutinised because of the by-catch associated with it. Populations of larger sea creatures including endangered sea turtles, dolphins and sharks are of particular concern.
Numerous regulations have been put into place since 2003 to ban the use of driftnets in the Mediterranean Sea. They have been made illegal by several laws, yet they are still widely used and some driftnet fleets are even expanding.
Morocco has admitted to operating over 300 drift netting vessels. Other fleets include the Italian fleet, numbering 90-100 vessels, the Turkish fleet comprising 45-100 vessels and the French fleet of between 45 and 75 vessels.
Aquaculture is expanding rapidly - often without proper environmental assessment - and currently accounts for 30 percent of the fish protein consumed worldwide.
The industry claims that farmed seafood lessens the pressure on wild fish stocks, yet many of the farmed species are carnivorous, consuming up to five times their weight in wild fish.
Mediterranean coastal areas are already over exposed to human influence, with pristine areas becoming ever scarcer. The aquaculture sector adds to this pressure, requiring areas of high water quality to set up farms. The installation of fish farms close to vulnerable and important habitats such as seagrass meadows is particularly concerning.
Aquaculture production in the Mediterranean also threatens biodiversity through the introduction of new species to the region, the impact of the farms' organic and chemical effluents on the surrounding environment and coastal habitat destruction.
In order to meet the growing demand for high-grade tuna meat in Japan, tuna ranching has developed in the Mediterranean, increasing the strain on the already depleted stocks.
A tug towing a tuna cage between fishing grounds in Libya and tuna farms in Sicily.
Juvenile tuna are caught and put into pens to fatten up. It takes up to 20 kilograms of bait to produce just one kilogram of tuna. The bait is made from other fish species, predominantly caught around West Africa, the North Atlantic and US waters.
Tuna ranching is fundamentally unsustainable but it also carries other risks. The 'foreign' bait used can introduce diseases to the local fish populations, as happened in Australian tuna ranches. The spread of disease to important local fish stocks such as anchovy or sardine could be disastrous for local fishermen.
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